Accretion definition, an increase by natural growth or by gradual external addition; growth in size or extent. See more.
Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream. Learn more about how they function and quiz your knowledge at the end.
Function of Alveoli. We breathe in oxygen so that parts of our body can use it for many different cellular functions. But we must somehow get the oxygen from our lungs into our bloodstream, so it can be transported to the many places it is needed. Likewise, our bodies produce carbon dioxide as a waste product.